More than 3,000 workers with Unite Here! Local 2 participated in the vote, and 92 percent of them voted to authorize the strike, which could deal a blow to San Francisco's tourism industry, according to Riddhi Mehta, spokeswoman for the union.

The union is negotiating separately with each of the 31 hotels where its members work, including those owned by Hyatt, Hilton, Marriott, Starwood and Intercontinental.

The last strike, in 2004 was devastating to the city's economy. That was a two week strike, a 53-day lockout and included a boycott of San Francisco hotels. This current contract dispute involves nearly 9,000 workers.

They are the cooks, the housekeepers, the bus boys and bellmen at San Francisco's hotels.

They have been without a contract since August and are voting on Thursday on whether to authorize a strike. Hotels say health care is the key issue.

"The cost of health care is just escalating beyond what anybody can afford anymore. Five or six years ago, it was about $600-$700 a month. Right now it is costing hotel owners close to $1,100 a month per employee," said Starwood Hotels Attorney Richard Curiale.

Workers are now being asked to pick up some of the cost. Elena Duran is a server at the Palace Hotel.

"I'm not a full-time worker. I'm part-time since my hours are reduced, since the economy. I'm not going to be able to afford it," she said.

Union leaders say health care is not the only sticking point.

"It's the fact that they are seeking to load a lot more work on a lot fewer people. They want short shifts, they want to combine a dozen jobs into five," said the president of the Hotel Workers Union Mike Casey.

Hotel taxes and other visitor generated fees contributed $528 million to the city coffers last year. The Chamber of Commerce says a strike would be devastating.

"We just hosted Oracle World, we just hosted the President's Cup and Fleet Week. We're starting to get some traction. The last thing we need is to give visitors a reason to stay away," said Steve Falk from the San Francisco Chamber of Commerce.

According to one estimate, the hotel strike in 2004 cost the city between $50 and $100 million. Mayor Gavin Newsom backed the workers in that dispute, even walking the picket line. He says he's been meeting with both sides for nearly a year.

"I think the conditions that lead to a strike and a lockout four years ago are very different from the conditions that exist today, and that's why I believe there will be some disruptions. Count on that over the next few months, but we'll work it out," said Mayor Newsom.

Keep in mind, even though members voted to authorize a strike, that doesn't mean one is imminent. Still, one tourism industry analyst says just the uncertainty is often enough to cause business groups, which book years in advance, to shy away from scheduling conventions.